Kudu条件UPSERT INTO

Question

Kudu是否支持UPSERT INTO的UPDATE部分的条件

我是否可以提供一个条件子句，根据插入值和目标表之间的比较，仅更新给定值？实际的用例是用最新的数据更新时间戳列。

这是我想象中的行为。

CREATE TABLE my_first_table
(
  id INT,
  name STRING,
  status INT,
  PRIMARY KEY(id)
)
PARTITION BY HASH PARTITIONS 4
STORED AS KUDU;

INSERT INTO my_first_table VALUES (1, "lee", 101), (2 "shiv", 102), (3,"bob", 103);

--CONDITION FALSE, UPDATE NOT PERFORMED
UPSERT INTO my_first_table AS t 
VALUES (3, "bobby", 100) AS v 
WHERE v.status > t.status

+----+------+--------+
| id | name | status |
+----+------+--------+
| 1  | lee  | 101    |
| 2  | shiv | 102    |
| 3  | bob  | 103    |
+----+------+--------+

--CONDITION TRUE, UPDATE PERFORMED
UPSERT INTO my_first_table AS t 
VALUES (3, "bobby", 100) AS v 
WHERE v.status < t.status

+----+------+--------+
| id | name | status |
+----+------+--------+
| 1  | lee  | 101    |
| 2  | shiv | 102    |
| 3  | bobby| 100    |
+----+------+--------+

在3不存在的情况下，它应该插入。

如果没有，是否有一个优雅的解决方案？

Answer 1

我发现的一个解决方案是在SELECT表达式中使用LEFT JOIN和过滤器。因此，假设我们有一个与目标表相同的表to_upsert，其中包含所有可能的upsert...

INSERT INTO to_upsert VALUES (3, "bobby" 100), (5, "newgal", 600);

UPSERT INTO my_first_table
SELECT to_upsert.id, to_upsert.name, to_upsert.status
FROM to_upsert
LEFT JOIN my_first_table ON to_upsert.id = my_first_table.id
WHERE my_first_table.status > to_upsert.status OR my_first_table.id IS NULL;

SELECT * FROM my_first_table;
+----+--------+--------+
| id | name   | status |
+----+--------+--------+
| 3  | bobby  | 100    |
| 1  | lee    | 101    |
| 2  | shiv   | 102    |
| 5  | newgal | 600    |
+----+--------+--------+

感谢收看本期“看我学sql”节目。